Introduction
Man’s study of Astronomy dates back to the pre-history period. Man was driven by many things to study Astronomy. One of these reasons was for religious purposes. Some heavenly bodies were considered as gods especially the sun. Besides, man studied Astronomy to help him come up with a calendar and predict seasons for farming and other purposes. Moreover man was driven by a curiosity to understand the universe.
The early study of astronomy mainly centered on observing visible heavenly bodies like the stars, the moon and planets that could be seen by the naked eye. The pattern and movement of these heavenly bodies was also observed. By observing the movement of heavenly bodies, they could differentiate between stars and planets since unlike stars that remained relatively in fixed positions, planets changed their positions. The early study of astronomy laid a framework for study that has progressively grown to our current knowledge of the universe.
We find astronomy study in one of the earliest civilizations of mankind-Mesopotamia. This was an area between River Tigris and Euphrates. Mesopotamia is considered to be the source of Western Astronomy. The presence of many star names in Mesopotamia tells us these people studied astronomy probably before they even learned to write. Mesopotamians interwove myth and religion to worship planets which were considered to be gods. Priests, commonly called Chaldeans practiced divination and astrology. Sumerians developed a form of mathematics that could predict variations in length of daylight during a year. There are written records in cuneiform that give us significant information about Sumerian astronomy. The earliest of these records is recorded in tablets called the Enuma Anu Enlil.
Sumerians made various discoveries in Astronomy. For example, they discovered the 18 year cycle of the lunar eclipse. They also developed texts that could predict the motions of planets based on past observations. They developed this discovery to come up with a mathematical model that could predict planet motions without referring to past records.
Like in Samaria, we find great astronomical works in ancient Egypt. For example, Egyptian pyramids point towards the pole star something that shows awesome observation skills of the heavens. Like Sumerians, astronomy played an important role in religion and calendar. Egyptians developed instruments that could be used to view heavenly bodies. One instrument was a plumb line. This was used together with a branch from a palm tree with a slit for viewing. Egyptians also developed a very accurate method for fixing hours on different days by referring to a fixed star.
Ancient India developed an astronomy that is commonly referred to as sidereal astronomy. This is based on the movement of bodies around the sun relative to the stars. The main purpose for observing movements of heavenly bodies was to establish times for ritual events. Like their Sumerian counterparts, Indian astronomers developed an accurate system that could be used to predict a lunar eclipse. They also developed a mathematical system that considered the earth to orbit on its own axis and related the movements of planets relative to the sun. Besides, they also accurately determined the earth’s diameter hence circumference and also found out about the positions of the sun, the earth and the moon during a lunar and solar eclipse. During a period known as the golden age of astronomy in India, Astronomy was greatly developed. Star catalogues were developed during this period.
Astronomy was developed to very complex levels In Ancient Greece. Eudoxus of Cridus and Callipus of Cyzicus developed geometrical and three dimensional models In the Fourth century B.C. Plato and Aristotle developed a philosophy that tried to explain reasons behind motions of heavenly bodies instead of developing predictive mathematical models. Greeks improved on their geometrical model based on concentric circles to one based on eccentric circles. Development in this study enabled Greeks to come up with their first star catalogue. A man named Erathonseses estimated the earth’s circumference to a high degree of accuracy using shadows at widely separated regions. Among great inventions in this empire was the development of a device that could calculate the motion of planets.
Another area where astronomy was developed and enhanced was in China. The Chinese could predict times when eclipses would occur and times when comets could be seen among other things. Their Astronomy was mainly for seasonal purposes. They developed different yearly calendars to reflect the changing cycles of the sun and the moon. In religion, divination was practiced using astronomical knowledge. Chinese astronomers are thought to be the first astronomers to observe and note a supernova.
Under great civilization, the Islamic world did great work in astronomy. They translated astronomical works of Greece and China into Arabic. Albumasar developed a mathematical model that took planets to move in heliocentric revolutions around the sun. Another astronomer named Azoph carried out an extensive study of stars and their constellations. In his book of Fixed Stars, he gave information on positions, color and brightness of stars including drawings for constellations. He also described the presence of a little cloud which has come to be known as a one of existing galaxies.
Astronomers made great discoveries in this era. They determined the position of the earth’s axis relative to the sun and estimated the length of a year to a very high degree of precision. They also made the first effort to introduce physics into astronomy. To do this, they carried out experiments that combined with mathematical models to draw conclusions. Through these efforts, they discovered many things key among them the fact that the moon emitted light to the earth at points in which the sun’s rays struck it. Muslims made many other advances in astronomy including the construction of a research institute at Baghdad.
Using geometrical techniques that were traditional in astronomy, Nicolaus Copernicus brought renaissance to astronomy. He showed that planets moved around the sun but not around the earth as previously thought. More work was done on this proposition and improved by Galileo and Johannes Kepler. Galileo was one of the earliest people to use the telescope. In 1610, he discovered the largest four of Jupiter’s moons. This was an important discovery because satellites were not known to orbit around planets by then. He constructed a telescope that had greater magnification capacity that enabled him to take important sightings. He was able to observe craters on the surface of the moon. These observations repealed the previous model of the earth being the centre of the universe. They in turn defended Copernicus model of the universe.
An important step in the study of astronomy was to fully unite astronomy with physics. Kepler was the first person to consider mathematical models that predicted the motions of planets with physical causes of these motions. He developed models that could predict movements of heavenly bodies from physical causes. More studies in this area were done by Isaac Newton. He came up with the law of Universal gravitation which he explained existed between heavenly bodies just the same way it attracted objects to the surface of the earth.
From the late 20thy century to present, more advancement has been made in the study of astronomy. The development of quantum physics has enabled scientists to note elements present in the sun and other heavenly bodies through the observation of spectral lines. Through use of photography, fainter objects in space can be seen. We now know that we live in a galaxy with more than ten billion stars. This is among other galaxies that exist in our universe. These galaxies have been shown to move continuously away from our planet. Stars have also been shown to be similar to the sun in may respects. They however have a different range of size, mass, temperatures among other things.
There is still room for improvement and more discoveries in the field of astronomy. For example, Einstein’s theory of relativity suggests that there could be existing black holes in our universe. These are collapsed stars that attract everything into them. Time and space ceases to exist in these black holes. Mankind knowledge in astronomy is expected to increase in the future. (Pennekoek)
Conclusion
With limited tools, knowledge and resources, people in the past embarked on studying and increasing their knowledge of the universe. We now enjoy knowledge that has been tested, improved and expanded. With an array of resources like satellites, spacecrafts, computers among others, we may feel most confident in our understanding of the universe. More study however needs to be done. With every new discovery we make, the seemingly infinite and amazing universe presents new challenges that test our understanding.
Works Cited
Pennekoek, Anton. A History of Astronomy. Dover Publication, 1989.Print.